This invention relates to an apparatus and process for separating a mixture of meat and shell parts derived from shellfish of the mollusk or bivalve type, and more particularly, to an apparatus and process for separating the meat and shell parts by elutriation procedures.
Bivalve or mollusk type shellfish, such as clams, scallops, oysters and mussels are well known and the meat of such shellfish is much in demand by the purchasing public. The processing of such shellfish to recover the meat from the shell parts however, is expensive and, in some cases, the procedures followed produce a product which to many customers is unacceptable.
In the usual commercial practices that are followed in recovering the edible meat product from the raw shellfish, the bivalve is subjected to a cleaning process for removing the dirt and debris which accompanies its recovery from its water habitat. To open the shell and reduce the adherence of the meat particles to the shell halves, the bivalve is also usually subjected to a steam treatment procedure which sometimes follows but which may be carried out simultaneously with the cleaning procedure. Thereafter the opened bivalve in the more modern commercial practices is passed through an apparatus which is commonly referred to as a "sheller" and which basically serves to sever the bivalve into two shell halves or parts while also overcoming the adherence of the meat particles to the shell halves. The shell parts that are mixed with the meat particles derived from the sheller are mainly in the form of shell halves although the mixture also contains a small amount of shell bits that result from the breakage of the shells and shell halves during the handling thereof. There are various ways to separate the shell parts from the meat particles other than by hand, and one way which has been used in the past is to float the meat particles away from the shell parts through the use of a brine solution. Such procedures tend to produce a meat product which is heavily permeated by the brine solution and which is unacceptable to many customers. Yet other ways to separate the shell parts and meat particles is to accomplish the separation mechanically as through the use of screens or other foraminous equipment. Such equipment is bulky however and not only takes up quite a bit of space that is valuable, as for example when the apparatus is to be operated on board a ship, but is also expensive to run.
Among other procedures which have been advocated for separating the meat particles from the shell parts is one in which the mixture is subjected to flotation procedures and during which the meat particles are floated to the surface of the water through the use of air bubbles in a flotation tank while the shell halves and shell bits gravitate downwardly in the tank to a conveying device which transports the shell parts to the exterior of the flotation tank. This method of separating the meat particles from the mixture has the disadvantage among others that separate means are required to gather and withdraw the meat particles from the flotation tank. Such equipment also takes up an excess amount of floor space and is unsatisfactory for use on board ship because of the interference with the flotation procedure that is attributed to the ship motion.